Generally, LEDs need to be carried on the packaging construction for applying to different kinds of electronic devices. For different LEDs, the packaging construction has to be modified correspondingly in order to increase the efficiency of the LEDs. For example, if the packaging construction only provides a flat plane to carry the LED, the light emitted from the laterals of the LED might not be utilized but wasted. More particularly, as referred to the plane provided by the packaging construction, the lights emitted from the LED can be roughly classified as vertical lights and horizontal lights. In the prior art, to utilize the horizontal lights (parallel to the plane provided by the packaging construction), the packaging construction is disposed with a cavity and the cavity is daubed with a reflection layer, and the LED is then placed in the cavity. In this way, the horizontal lights emitted from the LED can be reflected by the reflection layer daubed on the inner wall of the cavity and then emit perpendicular to the plane provided by the packaging construction, which increases light utilization efficiency.
However, in the prior art, the substrate of the packaging construction is generally made of plastic for reducing costs, which decreases the heat-dissipation performance of the substrate. When the LED is of high-power LED, this kind of packaging construction is not able to dissipate heat generated from the high-power LED effectively, causing the overall temperature to rise and further breaking down the packaging construction because of the accumulated heat (thermal breakdown). Therefore, in the prior art, ceramic substrates or silicon substrates are used to replace the plastic substrates for solving heat dissipation problem. However, the ceramic substrates can dissipate heat effectively but the cost of the ceramic substrates is too expensive, and the silicon substrates cannot reduce the dimension of the cavity corresponding to the dimension of the LED because of the fabrication limits.